Scientists have successfully demonstrated a machine that has allowed a man with locked-in syndrome to ’speak’ by transmitting his thoughts to a synthesizer via a wireless brain-machine interface. The volunteer for the demonstration, a 26-year-old man, had electrodes implanted in his brain five years ago. The researchers waited for his brain to grow around the electrodes. The electrodes convert neural impulses to FM radio signals, which are picked up by two coils across his scalp which act as an antenna. The radio signals are then sent to a decoder, which converts the neural impulses to digital data, which is routed to a computer that synthesizes the data into speech. The whole process takes about 50-milliseconds, the same amount of time it takes a person without any neural deficiencies to verbalize their thoughts.
The wireless component of this type of system mitigates the risk of infection.
So far, the system has been able to verbalize a small set of vowels, but the researchers are confident they can increase that to a broad array of consonants. The volunteer’s speech was interpreted successfully about 70% of the time, with that rate increasing significantly after training sessions. The last reported session had a record 89% accuracy.